this derivation will be built:
  /nix/store/1bshrbm1zywnhjy0fnq6c0vnrxs3abrl-ir-standard-fonts-unstable-2017-01-21.drv
error: Cannot build '/nix/store/04p71ga2gfdi69cvr0law8waxr3yjinh-ir-standard-fonts-unstable-2017-01-21.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/8cky3bj1f2qrwvj14sx9i9gx43qcin6g-ir-standard-fonts-unstable-2017-01-21
       Last 7 log lines:
       >
       > trying https://github.com/morealaz/ir-standard-fonts/archive/d36727d6c38c23c01b3074565667a2fe231fe18f.tar.gz
       >   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
       >                                  Dload  Upload   Total   Spent    Left  Speed
       >   0     9    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
       > curl: (22) The requested URL returned error: 404
       > error: cannot download ir-standard-fonts-unstable-2017-01-21 from any mirror
       For full logs, run:
         nix log /nix/store/04p71ga2gfdi69cvr0law8waxr3yjinh-ir-standard-fonts-unstable-2017-01-21.drv
error: build of resolved derivation '/nix/store/04p71ga2gfdi69cvr0law8waxr3yjinh-ir-standard-fonts-unstable-2017-01-21.drv' failed